I think YC is not only about funding, but Networking. Funding itself is around 20K$. But value of meeting right people is priceless. So, definitely apply.

this is from FAQ: (http://www.ycombinator.com/faq.html)

- We've already taken some funding. Can we still apply? - Sure. We've funded many startups that have.

This might be also interesting for you: - We don't want funding, but will you give us advice?

- Unfortunately we can't. We've invested in so many companies that helping them takes up all our time. But we've collected some general advice in our library.